Nutrient and Silicon Isotope Dynamics in the Laptev Sea and Implications for Nutrient Availability in the Transpolar Drift.

Laukert, Georgi , Grasse, Patricia , Novikhin, A., Povazhnyi, V., Doering, Kristin , Hölemann, J., Janout, M., Bauch, Dorothea , Kassens, Heidi and Frank, Martin (2022) Nutrient and Silicon Isotope Dynamics in the Laptev Sea and Implications for Nutrient Availability in the Transpolar Drift. Open Access Global Biogeochemical Cycles, 36 (9). Art.Nr. e2022GB007316. DOI 10.1029/2022GB007316.

[thumbnail of 2022gb007316-sup-0001-supporting] Text
2022gb007316-sup-0001-supporting - Supplemental Material
Available under License Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0.

Download (7MB)
[thumbnail of 2022gb007316-sup-0002-table] Text
2022gb007316-sup-0002-table - Supplemental Material
Available under License Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0.

Download (83kB)
[thumbnail of Global Biogeochemical Cycles - 2022 - Laukert.pdf]
Preview
Text
Global Biogeochemical Cycles - 2022 - Laukert.pdf - Published Version
Available under License Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0.

Download (3MB) | Preview

Supplementary data:

Abstract

Realistic prediction of the near-future response of Arctic Ocean primary productivity to ongoing warming and sea ice loss requires a mechanistic understanding of the processes controlling nutrient bioavailability. To evaluate continental nutrient inputs, biological utilization and the influence of mixing and winter processes in the Laptev Sea, the major source region of the Transpolar Drift, we compare observed with preformed concentrations of dissolved inorganic nitrogen (DIN), phosphorus (DIP), silicic acid (DSi) and silicon isotope compositions of DSi (δ30SiDSi) obtained for two summers (2013, 2014) and one winter (2012). In summer, preformed nutrient concentrations persisted in the surface layer of the southeastern Laptev Sea, while diatom-dominated utilization caused intense northward drawdown and a pronounced shift in δ30SiDSi from +0.91 to +3.82 ‰. The modeled Si isotope fractionation suggests that DSi in the northern Laptev Sea originated from the Lena River during the spring freshet, while in the southeastern Laptev Sea it was continuously supplied by it during the summer. Primary productivity fueled by river-borne nutrients was enhanced by admixture of DIN- and DIP-rich Atlantic-sourced waters to the surface, either by convective mixing during the previous winter or by occasional storm-induced stratification breakdowns in late summer. Substantial enrichments of DSi (+240 %) and DIP (+90 %) beneath the Lena River plume were caused by sea ice-driven redistribution and remineralization. Predicted weaker stratification on the outer Laptev shelf will enhance DSi utilization and removal through greater vertical DIN supply, which will limit DSi export and reduce diatom-dominated primary productivity in the Transpolar Drift.

Key Points

- Surface DIN, DIP, DSi and Si isotope dynamics are controlled by marine and riverine inputs and uptake by phytoplankton

- Strong DIP and DSi enrichments beneath the Lena River plume are due to sea ice-driven nutrient redistribution and remineralization

- Enhanced DSi utilization in the Laptev Sea will lead to a reduced diatom-dominated primary productivity in the Transpolar Drift

Document Type: Article
Funder compliance: BMBF: 03F0776 ; BMBF: 03G0833
Keywords: Nutrients, Silicon Isotope Dynamics, Laptev Sea, Nutrient availability, Transpolar Drift
Research affiliation: Woods Hole
HGF-AWI
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Kiel University
Corresponding Author:
Corresponding Author Name
GEOMAR ID
Affiliation
Laukert, Georgi
Laukert, Georgi
FB1-P-OZ Paleo-Oceanography
Main POF Topic: PT2: Ocean and Cryosphere
Refereed: Yes
Open Access Journal?: No
Publisher: AGU (American Geophysical Union), Wiley
Related URLs:
Projects: Laptev Sea System
Date Deposited: 20 Sep 2022 12:58
Last Modified: 28 Sep 2022 07:36
URI: https://oceanrep.geomar.de/id/eprint/57033

Actions (login required)

View Item View Item